The present invention relates to an instrument panel having a built-in instrument panel for an air bag device and, more particularly, to an instrument panel having an air bag door formed integrally and a process for manufacturing the instrument panel.
An air bag device is a device for restraining a vehicular passenger by inflating an air bag. The air bag device is ordinarily confined in a folded state in an instrument panel. At an emergency, the air bag is inflated to cleave the instrument panel partially so that it may be allowed to expand in front of the passenger.
In the instrument panel, therefore, a portion in front of the air bag device, that is, the portion confronting opening of an air bag case is so formed that it can be cleaved by expansion of the air bag.
The instrument panel is basically constructed by overlaying a solid backing layer of a synthetic resin holding the shape of a instrument panel on the back face of a surface member backed generally with a foaming resin layer. In the instrument panel having the built-in air bag device, a thinned linear portion is formed partially in the surface member in front of the air bag device so that it may be cleaved by the expanding pressure of the air bag.
However, the thinned portion to be cleaved appears as a linear relief on the surface of the instrument panel so that it acts as a parting line to exert a designing restriction on the instrument panel.
The invention has been conceived in view of the background thus far described and has an object to extend the degree of designing freedom of an instrument panel including a surface member having a two-piece structure of two tones, by making positive use of a joint of the two pieces of the instrument panel as a cleaved portion of an air bag device, and to improve positioning and fitting accuracies and shaping properties at the joint.
In order to achieve the above-specified objects, according to a feature of the invention, there is provided an instrument panel for an air bag device, comprising a surface member, and a foamed member formed on the back side of said surface member, so that the instrument panel may be partially cleaved by expanding pressure of an air bag of the air bag device, confined therein. A cleaved portion is set in an adjoining portion of a plurality of surface components of the surface member, wherein there is formed at adjoining side end portions of the surface components an engaging portion for partial engagement to join the surface components. The engaging portion includes a fitting groove having a generally U-shaped section formed by extending the end portion of one of the surface components to a side of the foamed member, and a fitting protrusion formed by extending the end portion of the other surface component to the side of the foamed member, and adapted to be inserted into the fitting groove, and wherein the foamed member is foamed and shaped with the fitting protrusion being inserted into the fitting groove.
When the instrument panel of the invention is to be manufactured, a process comprises: forming a setting plate to be inserted into the fitting groove of the surface component, such that it can go into and out of the inside of a bottom mold part; fitting said fitting groove on the setting plate while fitting the fitting protrusion of the adjoining surface component in the fitting groove; injecting a foaming material to the back sides of the surface components to foam the foaming material; and retracting the setting plate into the bottom mold part in the foaming course so that the fitting groove and the fitting protrusion may be brought into close contact with each other by the foaming pressure.
Another manufacture process of the invention comprises: inserting the fitting protrusion of the surface component into the fitting groove of the adjoining surface component; temporarily jointing the surface components by spot-fusing the same partially; arranging the temporarily joined surface components on the surface of a bottom mold part; and injecting a foaming material to the back sides of the surface components to foam the foaming material so that the fitting groove and the fitting protrusion may be brought into close contact with each other by the foaming pressure.
Here, the xe2x80x9cgenerally U-shapexe2x80x9d should include an upper opened U-shape, V-shape or C-shape.
In the instrument panel of the present invention having the two-piece surface structure of the two tones or different kinds of materials, the joint between the two-piece surface components provides the cleaved portion of the air bag device. This makes it unnecessary to form the thinned portion to be cleaved but possible to improve the degree of freedom for designing the instrument panel.
Moreover, the surface components are joined at their end portions by the fitting groove having the generally U-shaped section and the fitting projection to be fitted in the former. This U-shaped fitting makes it possible to prevent the foaming material from flowing to the mating faces of the joint. Moreover, the foaming pressure of the foaming material can enhance the close contact between the fitting groove and protrusion.
Still moreover, the fitting of the surface components at their end portions facilitates the setting, of the surface components on the mold so that the positioning and fitting accuracies of the joint can be improved.